Molded case industrial-type circuit breakers having a wide range of ampere and voltage ratings are available within a standard size breaker case geometry. This is made possible by relatively minor variations in the breaker components in order to keep the overall breaker geometry constant. The concept of "current limiting", wherein the movable contact arm is pivoted independently of the breaker operating mechanism, allows for circuit interruption early within the current waveform. Less current is then available when the operating mechanism responds to the overload. The steady state current carrying components, such as the contacts, contact arm and flexible braid conductor, must be enlarged when the breaker rating is increased in order not to become heated under steady state current conditions at the higher rating. One efficient method for allowing the movable contact arm to respond independently of the trip unit early in the current waveform is by the means of a U-shaped contact braid conductor. The opposing magnetic fields generated within the parallel legs of the U-shaped connection provides sufficient repulsive forces to propel the movable contact arm into its open position. Since most industrial circuit breakers are used in a three-phase arrangement with each phase having its own movable contact arm, it is expedient for the operating mechanism to open all three phases as quickly as possible.
In most molded case industrial-type circuit breakers, an intermediate latch is often employed along with the main latch to ensure that the breaker does not trip upon spurious conditions of overload. However, when the breaker is called upon to trip under short circuit conditions, some time is involved for the intermediate latch to release the cradle surface before the operating mechanism can become untoggled to open the breaker contacts. An efficient arrangement for rapidly releasing the intermediate latch from the cradle is described within U.S. patent application Ser. No. 500,643 filed June 2, 1983 and entitled "Circuit Breaker Assembly For High Speed Manufacture". This application is incorporated herein for purposes of reference.
The purpose of this invention is to provide an arrangement for rapidly displacing the intermediate latch from the cradle by interacting the trip bar with the intermediate latch.